Abrading tools are used to size and surface finish holes during a machining operation in which an abrasive insert of the tool is inserted into the hole and rotated to machine the hole. A relatively small amount of material stock is usually removed during this type of machining operation since the abrasive grit size is normally sufficiently small so as to provide a smooth surface finish.
One type of abrading tool which is disclosed by the prior art utilizes an abrasive member and a carbide shoe or utilizes two or more abrasive members mounted for radial movement with respect to each other so that the tool can be inserted within the hole and then expanded to perform the machining operation as the tool is rotated. Machining takes place within the hole as the expanded tool is rotated. Such tools are disclosed by U.S. Pat. Nos. 1,841,343; 1,874,856; 1,903,343; 1,910,658; and 1,960,555.
Another type of abrading tool incorporates a sleeve having an axial slit which has a circumferential component of about 360 degrees or less. An abrasive or lapping compound can be supplied to the sleeve during tool rotation to perform abrading by what is referred to as lapping. Also, an abrasive grit can be secured to the sleeve to perform the abrading as the tool is rotated. Mounting of the sleeve on a tapered arbor and axial positioning therealong allows the diameter of the sleeve to be controlled as the width of the slit in the sleeve varies according to the axial position. Such tools are disclosed by U.S. Pat. Nos. 2,341,094 and 3,462,887.
Other abrading tools are disclosed by U.S. Pat. Nos. 604,933; 1,906,190; 3,324,607; and 3,828,489.
It is very important that the abrading tools are of precise sizes so that the holes are machined to the required diameters. Also, the abrasive surface of rotatable abrading tools wears during use. Some provision for compensating for such wear is advantageous in order to increase tool life during which holes can be finished and sized to the same diameter.